GCN Circular 14196

F. Knust, J. Greiner, and V. Sudilovsky (all MPE Garching) report on 
behalf of
the GROND team:

We observed the field of GRB 130211A (Swift trigger 548276; Oates et al.,
GCN 14195
Not found
 
 
) simultaneously in g'r'i'z'JHK with GROND (Greiner et al. 2008,
PASP 120, 405) mounted at the 2.2 m MPG/ESO telescope at La Silla
Observatory (Chile).

Observations started at 03:45 UT on 11.02.2013, 9 min after the GRB trigger.
They were performed at a seeing improving over time from 3" to 1.2", and at
an average airmass of 1.0.

We find one variable source inside the 4.0" error circle, at coordinates
RA (2000.0) = 09:50:08.736
Decl (2000.0) = -42:20:32.64
with an error of 0.3".

Based on 1500s exposure in g'r'i'z' and 1200s in JHK started at 06:09 UT,
we estimate preliminary AB magnitudes of:

g' >  25.3 mag,
r' =  23.5 +- 0.1 mag,
i' =  22.2 +- 0.1 mag,
z' =  21.7 +- 0.1 mag,
J =  20.6 +- 0.2 mag,
H =  20.1 +- 0.2 mag, and
K >  19.5 mag.

Given magnitudes are calibrated against GROND zeropoints (g'r'i'z') as well
as 2MASS field stars (JHK) and are not corrected for the expected Galactic
foreground extinction corresponding to a reddening of E_(B-V)=0.53 mag in
the direction of the burst (Schlegel et al. 1998).

After correcting for the expected foreground extinction, the spectral 
energy distribution of this source
is well-fit by a power-law with slope b~1.4. The reduced flux in g' and 
r' imply a redshift of z~4.3.